Acoustic transducer having reduced thickness
A transducer for a hearing aid includes a housing, a relatively thin membrane having a free end suspended in the housing for vibration in response to a motor. The motor has a coil and a magnet assembly, the coil being mounted in the housing beneath the membrane; the magnet assembly being mounted in the housing coaxially with the coil and to one edge of the membrane.
This application is a divisional application of prior application Ser. No. 10/118,791, entitled “Acoustic Transducer Having Reduced Thickness,” filed Apr. 9, 2002, now allowed, which is incorporated herein by reference in its entirety.
FIELD OF THE INVENTIONThe invention relates to miniature receivers used in listening devices, such as hearing aids. In particular, the present invention relates to a receiver having one or more improved constructional features including, but not limited to a reduced thickness.
BACKGROUND OF THE INVENTIONA conventional hearing aid or listening device includes a microphone that receives acoustic sound waves and converts the acoustic sound waves to an audio (frequency) (electrical) signal. That “audio signal” is then processed (e.g., amplified) and sent to the receiver of the hearing aid or listening device. The receiver then converts the processed signal to a corresponding acoustic signal that is broadcast toward the eardrum.
A conventional hearing aid or listening device can include both a microphone and a telecoil for receiving inputs. The telecoil picks up electromagnetic (broadcast) signals. The telecoil produces a signal voltage across its terminals when placed within an electromagnetic field, which is created by an alternating current of an audio frequency electromagnetic signal moving through a wire. The signal in the telecoil is then processed (e.g. amplified) and sent to the transducer (or receiver) of the hearing aid for conversion to a corresponding acoustic signal.
A typical “hearing aid” comprises a combination of a receiver and a microphone in one housing or “case.” The signal from the microphone to the receiver is amplified before the receiver broadcasts the acoustic signal toward the eardrum.
In a typical balanced armature receiver, the housing or “case” is made of a soft magnetic material, such as a nickel-iron alloy. The case serves several functions: firstly, its housing provides some level of sturdiness; secondly, it provides a structure for supporting the components and their electrical connections. Thirdly, the case provides both magnetic and electrical shielding. Lastly, the case may provide acoustical and vibrational isolation to the other parts of the hearing aid.
The broadcasting of the acoustic signal causes the receiver to vibrate. The vibrations can affect the overall performance of the listening device. For example, the vibrations in the receiver can be transmitted back to the microphone, causing unwanted feedback. Furthermore, in a hearing aid with a telecoil, a magnetic feedback signal may create feedback problems. Consequently, it is desirable to reduce the amount of vibrations and/or magnetic feedback that occur in the receiver of the hearing aid or listening device.
Presently available moving armature transducers have a minimum thickness, based upon the usual manner of assembly of the various parts. Typical such transducers/receivers are shown in
A housing surrounds the working components of the receiver 10 and includes a case 14 and a cover 15. One end of the housing includes an output port 16 for transmitting the acoustical signal toward the users eardrum. An opposite end of the housing may include an electrical connector assembly 18 which may include provisions for various types of contacts or electrical connections such as by soldering or the like. This connector 18 receives an input audio frequency electrical signal that is converted by the internal working components of the receiver to an output acoustic signal (sound waves) which is broadcast from the output port 16.
The working components of the transducer or receiver 10 include a motor 20 which includes a magnet assembly 22 and a coil 24 which are coaxially located and in side-by-side abutting alignment. Through an axial center of the coil 24 and magnet assembly 22 is a moveable armature 12, which is moved in response to the electromagnetic forces produced by the magnet assembly 22 and coil 24 in response to the applied audio frequency electrical signal at the terminal 18. Thus, the corresponding motion of the armature 12 may be translated into acoustic energy (sound waves) by a diaphragm 30 which is mounted in the case 14 above the magnet assembly 22 and coil 24 and is operatively coupled with the armature 12 by a drive pin 32.
The overall thickness of the receiver 10 is defined by the thickness of the walls of the case 14 and cover 15, the thickness of the magnet assembly 22, which includes a magnet 26 and a magnet housing 28 surrounding the magnet 26, the diaphragm 30 and sufficient free airspace to permit vibration of the diaphragm to create acoustic energy or sound waves in response to the operation of the motor 20 as described above.
In hearing aids, it is generally desirable to decrease overall size of components where possible, and in particular, for hearing aides such as a behind the ear (BTE) hearing aid 40 (see
In the U-type armature, receiver 10a of
It is a general object of this invention to provide an improved transducer/receiver for a listening device, e.g., a hearing aid.
In accordance with one aspect of the invention, a transducer for a hearing aid comprises a housing, a relatively thin membrane suspended in said housing for vibration in response to a motor, said motor comprising a coil and a magnet assembly, said coil being mounted in said housing beneath said membrane; said magnet assembly being mounted in said housing coaxially with said coil to one edge of said membrane.
In accordance with another aspect of the invention, a dual transducer for a hearing aid comprises a pair of transducers mounted in side-by-side abutting relation, each of said transducers comprises a housing, a relatively thin membrane having a free end and suspended in said housing for vibration in response to a motor, said motor comprising a coil and a magnet assembly, said coil being mounted in said housing beneath said membrane; said magnet assembly being mounted in said housing coaxially with said coil and to one edge of said membrane, wherein each said housing comprises a case and a cover with said membrane being spaced beneath and parallel with said cover and wherein said transducers are mounted with said cases in congruently aligned and abutting condition.
BRIEF DESCRIPTION OF THE DRAWINGSIn the drawings:
While the invention is susceptible to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and will be described in detail herein. It should be understood, however, that the invention is not intended to be limited to the particular forms disclosed. Rather, the invention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims.
Several different embodiments of the invention, each with its own unique features and alternate embodiments, are described. Permutations and combinations of these features will, however, lead to further embodiments.
DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENT Referring now to the drawings, and initially to
Departing from the embodiments of
It will be noted that with minimal modification, the transducer 110 can be modified to act as a microphone with an incoming acoustic or sound pressure signal vibrating the membrane 130 and the membrane in turn imparting vibratory motion to the armature causing a corresponding change in the electrical magnetic field of the magnet and coil 120, 124 which can be translated into an electrical output signal. However, the present invention is illustrated and described herein primarily by reference to use of the transducer 110 as a receiver.
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In one embodiment of the invention, the magnet assembly 122 may be further improved by constructing the magnet 126 of a rare earth magnet material such as neodymium or samarium. The specifications of these materials are such that the same amount of magnetic flux can be achieved using less magnetic material, which further allows a decrease of the dimensions of the magnet and magnet housing assembly.
Referring again to
Dual receivers are commonly matched by magnetizing one or both in such a way that the sensitivities match at a certain frequency, usually 1 KHz or lower. For optimum performance, the receiver should be matched for output at a peak frequency or other predetermined frequency. This can be done by sorting the receivers into groups and selecting matching receivers according to the foregoing and/or other predefined criteria. The configuration wherein the magnet housing extends through the cover also helps in magnetizing the receivers for matching purposes, otherwise it would have to be done with the covers removed. Advantageously, in the embodiment of
While particular embodiments and applications of the present invention have been illustrated and described, it is to be understood that the invention is not limited to the precise construction and compositions disclosed herein and that various modifications, changes, and variations may be apparent from the foregoing descriptions without departing from the spirit and scope of the invention as defined in the appended claims.
Claims
1-16. (canceled)
17. A dual transducer for a hearing aid, said dual transducer comprising a pair of transducers mounted in side-by-side abutting relation, each of said transducers comprising:
- a housing, a membrane having a free end suspended in said housing for vibration in response to a motor, said motor comprising a coil and a magnet assembly, said coil being mounted in said housing beneath said membrane; said magnet assembly being mounted in said housing coaxially with both said coil and one edge of said membrane;
- wherein each said housing comprises a case and a cover with said membrane being spaced beneath and parallel with said cover and wherein said transducers are mounted with said cases in congruently aligned and abutting condition.
18. The dual transducer of claim 17 wherein each transducer further includes a printed circuit board and wherein said magnet assembly and said coil are mounted on said printed circuit board.
19. The dual transducer of claim 17 wherein each of said transducers is matched with the other of said transducers according to predefined criteria.
20. The dual transducer of claim 19 wherein said predefined criteria includes magnetizing at least one of said transducers so that the sensitivities of both transducers match at a given frequency.
21. The dual transducer of claim 20 wherein said given frequency is not greater than 1 KHz.
22. (canceled)
23. A transducer for a hearing aid, said transducer comprising:
- a housing, a relatively thin membrane having a free end suspended in said housing for vibration in response to a motor, said motor comprising a coil and a magnet assembly, said coil being mounted in said housing beneath said membrane;
- wherein said membrane is hingedly coupled with said housing.
24. The transducer of claim 23 and further including an armature extending through said coil and said magnet and a drive pin having one end coupled to said armature and having a second end coupled with said membrane.
25. The transducer of claim 24 wherein said membrane has a through opening through which said drive pin extends.
26. The transducer of claim 24 wherein said membrane has an edge recess through which said drive pin extends.
27. (canceled)
28. A transducer for a hearing aid, said transducer comprising:
- a housing, a relatively thin membrane having a free end suspended in said housing for vibration in response to a motor, said motor comprising a coil and a magnet assembly, said coil being mounted in said housing beneath said membrane;
- wherein said housing comprises a case and a cover, and further including flanges formed at lateral edges of said membrane and a quantity of damping paste applied between said flanges and each of a pair of respective opposed inwardly facing surfaces of said case.
29. The transducer of claim 28 wherein said membrane flange on one lateral edge is spaced from the facing wall of said case by a distance greater than the flange on the other edge, wherein said flanges extend into said case and further including a cap applied over said damping paste and along both of the lateral edges of said membrane.
30-38. (canceled)
39. The transducer of claim 17 wherein said one edge of said membrane is attached to said magnet assembly.
Type: Application
Filed: Jan 31, 2007
Publication Date: Jun 14, 2007
Patent Grant number: 7970161
Inventor: Aart van Halteren (Hobrede)
Application Number: 11/700,493
International Classification: H04R 25/00 (20060101);